Polyamide fibers, such as nylon fibers, are useful in producing many different and various textile products. In particular, polyamide fibers are well suited for constructing carpeting. For instance, nylon carpeting is durable, has good aesthetic properties and is relatively inexpensive. Further, nylon carpeting is very receptive to acid dyes and thus can be produced in a wide variety of colors.
Unfortunately, nylon carpeting and other polyamide products are susceptible to staining. For example, many food and beverage items, such as coffee, fruit juices, and wine, contain natural ingredients which can bind to dye sites located on polyamide materials. Further, many artificial colorants and pigments that are added to food and beverage products can also permanently stain polyamide fibers. Such colorants and pigments are typically added to powdered drink mixes, to gelatin desserts, and to various soft drinks.
In the past, many attempts have been made to make stain resistant polyamide fibers and, in particular, to produce stain resistant carpeting. For instance, in the past, carpet fibers have been coated with liquid resistant coatings which inhibit wetting of the carpet surface. These coatings, however, have a tendency to wear off over time.
In the past, polyamide carpet fibers have also been treated with stain blocking compositions that actually bind to available dye sites that remain on the fibers after the fibers have been dyed a particular color. For example, various sulfonated novolak resins have been used for this purpose. Novolak resins include syntans, resoles and generally comprise sulfonated phenol and napthalene formaldehyde condensates. In the past, sulfonated novolak resins have proven to be very effective in providing polyamide materials with stain resistant characteristics. Unfortunately, however, novolak resins have a tendency to discolor when exposed to sunlight or other sources of ultraviolet light. As a result, polyamide materials treated with sulfonated novolak resins, such as carpeting, can yellow or otherwise discolor over time. As such, a need currently exists for an improved stain blocking composition for polyamide materials that binds to available dye sites but does not significantly cause discoloration of the materials after application. Specifically, it would be particularly desirable if a stain blocking agent could be fabricated that would work in conjunction with sulfonated novolak resins in a manner so as to decrease the amount used and hence decrease discoloration when exposed to light.